Uterine abnormalities are structural or functional deviations from a typical uterine form that can impact reproductive health. These conditions range widely in origin and severity, often causing symptoms like abnormal bleeding or difficulty with pregnancy. Since the uterus is designed to house a developing fetus, any physical alteration can interfere with its complex functions. Recognizing these deviations is important for diagnosing and treating gynecological and fertility-related issues.
Classification of Uterine Abnormalities
Uterine abnormalities are broadly categorized based on when they originate, which guides diagnosis and treatment. The two primary groups are congenital anomalies and acquired conditions. Congenital anomalies are present from birth, arising during fetal development when the reproductive organs, often involving the Müllerian ducts, are forming. These are fixed structural defects. Acquired conditions manifest after birth, typically caused by hormonal changes, inflammation, surgical trauma, or abnormal tissue growth.
Congenital Uterine Anomalies
Congenital uterine anomalies, also known as Müllerian duct anomalies, occur when the paired ducts forming the female reproductive tract fail to develop, fuse, or resorb correctly. These structural defects can affect the uterus, cervix, and vagina. The most common is the septate uterus, which accounts for up to 35% of all congenital uterine malformations.
A septate uterus forms when the walls of the fused ducts fail to fully resorb, leaving a partition (septum) that divides the uterine cavity. This septum is poorly supplied with blood vessels, which may impair implantation and lead to recurrent miscarriage.
The bicornuate uterus results from a partial failure of the ducts to fuse, causing the upper part of the uterus to be distinctly indented, giving it a heart shape. A didelphys uterus, or double uterus, represents a complete failure of fusion, resulting in two entirely separate uteri, each with its own cervix. The unicornuate uterus arises from the failure of one duct to develop, resulting in a half-uterus with a single fallopian tube.
Acquired Uterine Conditions
Acquired uterine conditions develop in a previously normal uterus and are characterized by the growth of abnormal tissue or the formation of scar tissue.
Uterine Fibroids (Leiomyomas)
These are the most common non-cancerous tumors in people of reproductive age, arising from the smooth muscle cells of the uterine wall. Fibroids are responsive to estrogen and progesterone, which promotes their growth, explaining why they tend to shrink after menopause. They are classified by location: intramural fibroids are embedded within the muscular wall, while submucosal fibroids protrude into the uterine cavity and are often linked to heavy menstrual bleeding and infertility.
Endometrial Polyps
Polyps are localized overgrowths of the endometrial lining. They attach to the uterine wall and are also estrogen-sensitive. Polyps are a frequent cause of irregular or intermenstrual bleeding.
Asherman’s Syndrome
This condition involves intrauterine adhesions or scar tissue resulting primarily from trauma to the uterine lining. Damage, often caused by procedures like dilation and curettage (D&C), leads to the formation of fibrous bands that partially or completely obliterate the uterine cavity.
Reproductive Impact and Management
The presence of a uterine abnormality significantly affects reproductive outcomes by interfering with conception, implantation, and gestation. Conditions that distort the uterine cavity, such as a septate uterus, submucosal fibroids, or intrauterine adhesions, are frequently associated with recurrent miscarriage. The abnormal structure can hinder implantation or restrict the blood supply necessary for a healthy placenta.
Acquired and congenital anomalies also increase the risk of complications later in pregnancy, including preterm labor and delivery, and abnormal fetal positioning. For instance, the abnormal shape of a unicornuate or bicornuate uterus may not accommodate a full-term pregnancy. For those facing these reproductive challenges, surgical intervention is often the primary management strategy to restore normal uterine anatomy.
Hysteroscopy, a minimally invasive procedure using a small camera inserted through the cervix, is the standard approach for treating many intrauterine lesions. This technique allows for the precise removal of a uterine septum in a procedure called a septoplasty, which can reduce the risk of future miscarriages. Hysteroscopy is also used for targeted removal of endometrial polyps (polypectomy) and submucosal fibroids (hysteroscopic myomectomy). Myomectomy, the surgical removal of fibroids, can be performed hysteroscopically, laparoscopically, or abdominally, depending on the fibroid’s size and location, and is performed to alleviate symptoms. Asherman’s syndrome is treated with hysteroscopic adhesiolysis, where scar tissue is cut away to reopen the uterine cavity.